http://masterkeypro.com/ is sort of the only entry in the market and cores/companies-that-need-key-schedules change just often enough that say $5-10 month could gain traction.
Essentially inventory management for locks, including the specific bitting(s) for each lock? That actually sounds really fun to build, not terribly challenging, and probably has huge market reach.
One quick challenge though, my understanding is that the average org that needs this either contracts or has full time staff who manage their locks. Those are normally guys who manage this by placing the 10 cores they need to re-key on their work bench, maybe putting a tape label on, and then just going to the individual locks and dropping in a new core. I get the value as a management tool, but does this really improve things for the average staff locksmith?
Usually yes either they just go through some one like Hull Supply (the company I worked for) or they have their own department. Whoever they go through however still has to deal with this shit. Masterkey is fine if you already have a key schedule, it'll spit out as many pinning combos as it can.
at 300$ a license there's room for competition and if you could make a GUI that says calls to a prolog style logic engine to automatically create the keying hierarchy (Management needs keys to these doors, renters need keys to these doors, janitorial needs key to these doors, etc...) you could easily beat the functionality of Masterkey.
http://masterkeypro.com/ is sort of the only entry in the market and cores/companies-that-need-key-schedules change just often enough that say $5-10 month could gain traction.